Afghanistan: one of the most isolated and barren landscapes on earth is a strange place for an Empire or Superpower to invade. But for three of the greatest powers the world has seen, it became an unlikely target, an enduring obsession and an unwinnable war. After the British invasion in the 19th Century, Afghanistan was dubbed the 'Graveyard of Empires'. And yet two Superpowers, the Soviet Union and the US-led coalition today, again invaded in the 20th and 21st centuries. Rory Stewart is uniquely placed to tell this history - he ran a charity in Kabul for many years, and he walked across Afghanistan a month after the fall of the Taliban. In making these two films he meets Soviet Generals; former Taliban and Mujahideen commanders; CIA spies; historians and former diplomats. Filmed in Afghanistan, America, Russia and Great Britain, Rory Stewart tells the history of two centuries of foreign intervention in Afghanistan. So how has this history forged the Afghanistan of today, and what is it about this place, the paranoia and aggression of Empires, that's created this repeated tragedy?